An electronic throttle body throttle plate in a vehicle controls the air-fuel ratio within a combustion chamber of an internal combustion engine. Proper positioning of the throttle plate is critical for efficient engine operation. The throttle plate itself can move between a lower mechanical stop (LMS) position, in which the throttle plate is at an angular position of zero degrees (i.e., a completely closed throttle position) to a maximum travel position (i.e., a wide open throttle position). The amount of air entering the combustion chamber depends on the angular position of the control plate, and the proper throttle plate position for a given air-fuel ratio is dictated by a position of an acceleration pedal in the vehicle, which controls how much air and fuel enter the combustion chamber.
There are various conditions where the plate will not reach a desired position. For example, during low temperature conditions, it is possible for ice to form on the throttle plate or on a body in which the throttle plate operates. This ice formation will block movement of the throttle plate to its desired position.
Varying temperature conditions, friction, and/or changing battery voltages may also cause a calculated lower mechanical stop (LMS) position value (e.g., the position at which the position of the throttle plate is at, for example, zero degrees and where the throttle is completely closed) to change. Because mass air flow in the throttle body is calculated based on the LMS value, any inaccuracies in determining the LMS value will create inaccuracies in calculating mass air flow. However, currently known systems without EEPROMs cannot store the LMS values of previous driving cycles and instead recalculate the adaptation values each time the vehicle is turned on. Although the system does attempt to move the throttle plate to the LMS position before calculating the adaptation values, friction in the throttle body, fluctuating battery voltages, and other factors may cause the throttle plate position to be different than the actual LMS position. Moreover, the LMS position itself may change due to these conditions or as the system ages. This causes the adaptation values to be calculated incorrectly and cause inefficiencies in engine operation.
Moreover, the angular position of the throttle plate may be incorrect due to miswirings in the electronic throttle body control that may occur during vehicle assembly or component replacement. Miswirings may cause the throttle plate to move in a direction opposite to the desired direction. If the throttle plate is allowed to continue moving in an undesired direction, the resulting improper air-fuel ratio may cause adverse effects in the engine and potentially damaging vehicle operation.
There is a desire for an electronic throttle body control that ensures proper throttle plate positioning even under adverse or changing environmental conditions. There is also a desire for an electronic throttle body control that can adapt to any variations in the LMS value to ensure accurate throttle plate position.